html { font-size: 15.625vw; }
html, body { margin: 0 auto; }

@media only screen and (max-width: 320px) {
  html { font-size: 50px; }
  html, body { min-width: 320px; }
}

@media only screen and (min-width: 540px) {
  html { font-size: 84.375px; }
  html, body { max-width: 540px; }
}